System for automatically paying-out line proportional to extension of crane boom

ABSTRACT

In a hydraulic system, a proportional flow valve is used for automatically paying-out line as a crane boom is extended so that extension of the boom will not draw up the hook or cause damage if there is no free line. The proportional flow valve diverts to the winch motor some of the hydraulic fluid directed by a manual valve toward the boom-extending cylinder. The necessary pressure in the line to the winch motor, required for actuating a safety valve in the return line from the winch motor, is achieved through the use of a special reversing valve for the winch motor. This reversing valve has a combination closed and open center spool so that when centered it blocks the line to which fluid is diverted while leaving open the return line.

United States Patent Lado [72] Inventor: William .I. Lado, Rome, N.Y.

[73] Assignee: Pettibone Corporation, Chicago, Ill.

[22] Filed: May 1, 1970 [21] Appl. No.: 33,726

i [52] us. (:1. ..212/ss, 60/97 E [51] Int. Cl ..B66c 23/06 [58] Fieldof Search ..212/55; 60/97 E [56] References Cited UNITED STATES PATENTS2,051,434 3/1936 Cavagnaro .6019? E 2,343,912 3/1944 Lauck ..60/97 E X2,643,664 6/1953 Willet ..60/97 E 3,601,259 8/1971 Olson ..2l2/553,371,799 3/1968 Brownell ..2l2/55 3,315,820 4/1967 Stauffer ..212/55MOTOR MOIS PRDPORTIONAL (451 Oct. 31, 1972 FOREIGN PATENTS ORAPPLICATIONS 1,009,780 6/1957 Germany ..2l2/55 Primary Examiner-Evon C.Blunk Assistant Examiner--Merle F. Maft'ei Attorney-Barbe, Robertson &Vandenburgh [57] ABSTRACT In a hydraulic system, a proportional flowvalve is used for automatically paying-out line as a crane boom isextended so that extension of the boom will not draw up the hook orcause damage if there is no free line. The proportional flow valvediverts to the winch motor some of the hydraulic fluid directed by amanual valve toward the boom-extending cylinder. The necessary pressurein the line to the winch motor, required for actuating a safety valve inthe return line from the winch motor, is achieved through the use of aspecial reversing valve for the winch motor. This reversing valve has acombination closed and open center spool so that when centered it blocksthe line to which fluid is diverted while leaving open the returnADJUS'IABL E FL on REGULATDR SYSTEM FOR AUTOMATICALLY PAYING-OUT LINEPROPORTIONAL TO EXTENSION OF CRANE BOOM INTRODUCTION Hydraulicallyextendable booms for cranes have become very common and popular.Throughout their use, they have presented an attendant problem that whenthe boom is extended has the same effect as m drawing in the line. Aload hanging by the line is drawn closer to the tip of the boom, and ifthere is not enough free line something must give, and damage canresult. When the hook or the block by which it is carried is tightagainst the pulley or block at the tip of the boom, the line between thepulley and the winch binds the boom against extension. Although damagecould be prevented by setting the relief valve for the boom-extendinghydraulic fluid at a sufficiently low value, this is undesirable becausea higher value is sometimes needed. A long-practiced partial solution tothe problem is to place the boom extension and winch control valvehandles adjacent one another so that they could be operated with onehand. For inexperienced operators this is an unreliable and awkwardremedy. Even experienced operators can make mistakes. In some cranes,using one hand for these two valves may be objectionable.

Schemes known heretofore for automatically payingout the line as theboom was extended have not proved popular and perhaps have not reallybeen practicable.

According to the present invention, the line is automatically payed outas the boom is extended, with complete dependability and at lowequipment cost, by utilizing a proportional flow regulator connected todivert to the winch motor some of the hydraulic fluid which wouldotherwise be used entirely for extending the boom. This valve representssubstantially the only additional equipment cost required by thisinvention. Although the winch control valve needs a special spool, thisis merely furnished in place of that which would otherwise be used. Somevery inexpensive check valves may also be required, unless theirfunction is inherent in the proportional flow regulator.

Additional advantages and objects of the invention may be apparent fromthe following description and from the drawings.

DESIGNATION OF FIGURES FIG. 1 is a simplified side view of a mobilecrane having an extensible or telescopic boom with which the presentinvention may be used.

FIG. 2 is a diagrammatic circuit diagram representing the presentinvention.

DESCRIPTION OF SPECIFIC EMBODIMENT The following disclosure is offeredfor public dissemination in return for the grant of a patent. Althoughit is detailed to ensure adequacy and aid understanding, this is notintended to prejudice that purpose of a patent which is to cover eachnew inventive concept therein no matter how others may later disguise itby variations in form or additions or further improvements. The claimsat the end hereof are intended as the chief aid toward this purpose, asit is these that meet the requirement of pointing out the parts,improvements, or combinations in which the inventive concepts are found.

FIG. 1 illustrates a hydraulic truck crane mounted on a vehicle 10. Thecrane comprises a base 11 which usually can swing about a vertical axis.This carries a proximal boom section 12, sometimes called a shipper forpivotal movement about a horizontal pin 13. A distal boom section 14 istelescopically received in proximal boom section 12. A hydrauliccylinder 15 is connected between base 11 and boom section 12 to pivotthe boom about pin l3. A hydraulic motor 16, commonly called a crowdcylinder, is connected between boom sections 12 and 14 to control theextent to which they are telescoped with respect to each other. A hoistline 17 extends from a winch 18 about a pulley 19 on the end of theboom. Winch 18 is operated by a hydraulic motor 20. There may be morethan one distal or telescoping boom section, each operated by a crowdcylinder.

Referring to FIG. 2, the hydraulic cylinder defining motor 16 is doubleacting and has hydraulic connections 23 and 24. When fluid underpressure is supplied to connection 23, the boom is extended, i.e., boomsection 14 moves out from its nested position within boom section 12.When hydraulic fluid is supplied to connection 24, the boom isretracted, i.e., section 14 moves further within section 12. Aconventional reversing valve or manual control valve 25 has threepositions. It is resiliently urged toward the center of these threepositions by means such as springs 26. A conduit 27 connects valve 25with a source of fluid pressure as represented by pump 28. A conduit 28connects valve 25 with discharge, as represented by sump 30.

A conduit 32 connects valve 25 with connection 24. A conduit 33 connectsvalve 25 with a check valve 34 and with the input of a proportional flowregulator 35. One output 36 of the proportional control regulator isconnected by a conduit 37 to a check valve 38. A con duit 39 connectscheck valves 34 and 38 with cylinder connection 23.

The second output 43 of the proportional flow regulator is connected bya conduit 44 to a check valve 45. The constrictive orifices indicated onthe proportional flow regulator 35 are to indicate diagrammatically thatthe hydraulic fluid delivered to the input of the flow regulator throughconduit 33 are proportionally divided between the respective outputs 36and 43. In other words, a proportion of the flow valve 25 directs towardthe crowding function and diverted to the line pay-out function. Thescrew 46 associated with one of these orifices is to indicate that therelative proportion of the flow through each of the outputs of theregulator may be varied. One valve suitably used for proportional flowregulator 35 is that available from Fluid Controls as their No.2F24-P-6-6-6-40S.

Another reversing or manual control valve 49 has three positions and isresiliently urged to the center of the three positions, as suggested bysprings 50. A conduit 51 connects valve 49 to a suitable source ofhydraulic fluid, as indicated by pump 52. A conduit 53 connects thevalve to discharge, as indicated by sump 54. All sumps indicated areactually a common tank from which the pump can draw. Pressure line 51has a pressure relief valve 55 communicating therewith. A similarpressure relief valve 55 communicates with pressure line 27 from pump28.

A conduit 58 connects valve 49 with check valve 45 and with connection59 of motor 20. A conduit 60 connects valve 49 with a pilot-actuatedvalve apparatus 61. The valve apparatus 61 is connected by a conduit 62to a connection 63 on motor 20.

The valve apparatus 61 comprises a check valve 65 in parallel with anautomatically actuated valve 66. Valve 66 is controlled by a hydrauliccylinder 67 responsive to the pilot pressure in conduit 58, as indicatedby the fine line 58.

With the two valves 25 and 49 in their central position, as illustratedin FIG. 2, both of the motors l6 and are stationary. The fluid from pump28 is recirculating through the sump 30. The fluid from pump 52 likewiseis recirculating to sump 54. This fluid is applying some pressure in adirection tending to open check valve 65, but the pressure is relativelylow because of being open to the sump 54. Furthermore, the conduit 58 atthe opposite side of motor 20 is blocked at valve 49 and at check valve45. Thus, motor 20 is not operatmg.

1f the line 17 is to be wound on winch l8 (raising the load), valve 49is shifted to open connections represented by assuming that the rightend of the valve diagram is aligned with the conduits. This appliesfluid pressure to conduit 60 and connects conduit 58 to the sump 54.Thus, fluid pressure will flow through check valve 65, motor 20 andreturn through conduit 58. If the load is to be lowered, the valve 49 isshifted oppositely to open connections represented by the left hand endof the valve diagram so that fluid pressure is supplied to conduit 58and conduit 60 is connected to the sump. As conduit 58 is pressurized itactuates hydraulic cylinder 67 to open valve 66 so that the hydraulicfluid from motor 20 can flow through conduit 62, through valve 66 toconduit 60 and then to the sump.

1f the boom l2, 14 is to be retracted, the valve is moved to the left sothat fluid under pressure is applied to conduit 32 and conduit 33 isconnected to sump 30. Thus, the hydraulic fluid flows to connection 24of cylinder 16. The hydraulic fluid from the cylinder flows fromconnection 23 through check valve 34 to return to the sump throughconduit 33. A safety or pilot actuated valve similar to valve 61 wouldordinarily be present adjacent connection 33 but is omitted forsimplification.

If the boom is to be extended, the valve 25 is moved to the right sothat conduit 33 is connected to the pump 28 and conduit 32 is connectedto sump 30. Fluid from conduit 33 flows through the proportional flowregulator 35 to output 36 and through check valve 38 to connection 23 ofthe motor 16. The fluid from the motor, of course, discharges throughconduit 32 to the sump 30. However, a proportion of the fluid fromconduit 33 also flows to the second output 43 of the proportional flowregulator 35. This fluid proceeds through check valve 45 to conduit 58.As it pressurizes conduit 58 it opens valve 66 as previously describedso that the fluid from motor 20 can flow through 62, 60 and 53 to thesump 54. The pressurized fluid in conduit 58 being derived from theproportional flow regulator also flows through motor 20 to actuate motor20 in the direction such as to pay out the hoisting line 17.

As initially explained, if the hoisting line 17 was not payed out, therewould be a danger that something would be broken by the extension ofboom 12, 14. This can be visualized with reference to FIG. 1 where itwill be seen that if boom section 14 moves to the right the portion ofline 17 below pulley 19 will decrease drawing the block toward thepulley 19. Conceivably, these can be brought into contact by theextension of the boom, thereby resisting any further extension of theboom, so that if further extension were attempted, damage would result.However, through the use of the present invention, the line 17 is payedout as the boom is extended so that the extent of the line 17 outboardof pulley 19 is not significantly decreased and the danger of damage iseliminated. Theoretically, the adjustment of proportional flow regulator35 would be such that during extension of the boom block 70 would stayat a constant distance from pulley 19. Actually, such precision is notlikely to be obtained or constant, and the regulator 35 should thereforebe adjusted to cause a slight increase of the spacing of block 70 can bemade by operating valve 49.

Because of the proportional flow nature of valve 35 it accommodatesitself to varying rates of flow provided by valve 25 from "crackingopen" to full open. Throughout the range, it maintains at least roughlythe movement of 17 at least equal to the crowding movement of boomsection 14.

lclaim:

l. A hydraulic system for a crane having a boom which is telescopicunder control of a crowd cylinder having extend and retract conduits anda reversing crowd" valve to be extended when the valve passes pressuredfluid to its extend conduit leading to one cylinder port and makes aconnection for the other cylinder port to discharge;

the crane also having a hoist line extending in part longitudinallyalong the boom and paying out to lower a load under control of a winchmotor and a three-position reversing line" valve having up and downconduits when the line" valve passes pressured fluid to the down"conduit leading to the winch motor and makes a connection for the otherwinch motor conduit to discharge, said other conduit having apilot-actuated safety valve preventing flow through said other conduitfrom the winch motor to discharge except when pressured fluid issupplied to the down" conduit, characterized by:

a proportional flow regulator connected to receive fluid from the crowd"valve when in the crowd" setting and to proportion the flow thereofbetween the crowd motor for extending the boom and the line" motor meansfor paying out the line;

said three-position reversing "line" valve when in its middle positionblocking flow from the down conduit to discharge while providing apassage for flow from the other winch motor conduit to discharge.

2. A hydraulic system for a crane having a boom which is telescopicunder control of a crowd cylinder having extend and retract conduits anda reversing crowd valve to be extended when the valve passes pressuredfluid from a crowd pump to its extend" conduit leading to one cylinderport and makes a connection for the other cylinder port to discharge;the crane also having a hoist line extending in part longitudinallyalong the boom and paying out to lower a load under control of a winchmotor and a three-position reversing line" valve having up and downconduits when the line valve passes pressured fluid from a line pump,having its output separate from the output of the crowd pump, to the"down" conduit leading to the winch motor and makes a connection for theother winch motor conduit to discharge, said other conduit having apilot-actuated safety valve preventing flow through said other conduitfrom the winch motor to discharge except when pressured fluid issupplied to the down conduit, characterized by:

an adjustable proportional flow regulator connected to receive fluidfrom the crowd valve when in the crowd setting and to proportion theflow thereof between the crowd motor for extending the boom and theline" motor means for paying out the line; whereby the line is payed outwhen the boom is extended, but at a relative rate which is adjustable;

said three-position reversing "line" valve when in its middle positionblocking flow from the down" conduit to discharge while providing apassage for flow from the other winch motor conduit to discharge.

3. A hydraulic system for a crane having a boom which is telescopicunder control of a crowd cylinder having extend and retract conduits anda reversing crowd valve to be extended when the valve passes pressuredfluid from a crowd pump to its extend" conduit leading to one cylinderport and makes a connection for the other cylinder port to discharge;the crane also having a hoist line extending in part longitudinallyalong the boom and paying out to lower a load under control of a winchmotor and a three-position reversing line valve having up and downconduits when the line valve passes pressured fluid from a line pump,having its output separate from the output of the crowd pump, to thedown" conduit leading to the winch motor and makes a connection for theother winch motor conduit to discharge, said other conduit having apilot-actuated safety valve preventing flow through said other conduitfrom the winch motor to discharge except when pressured fluid issupplied to the down" conduit, characterized by: an adjustableproportional flow regulator connected to receive fluid from the crowdvalve when in the crowd setting and to proportion the flow thereofbetween the crowd motor for extending the boom and the line" motor meansfor paying out the line, whereby the line is payed out when the boom isextended, but at a relative rate which is adjustable; saidthree-position reversing line" valve when in its middle positionblocking flow from the down conduit to discharge: but said valvesproviding a passage for flow from the other winch motor conduit todischarge when the crowd valve is set for extending the boom.

1. A hydraulic system for a crane having a boom which is telescopicunder control of a crowd cylinder having extend and retract conduits anda reversing ''''crowd'''' valve to be extended when the valve passespressured fluid to its ''''extend'''' conduit leading to one cylinderport and makes a connection for the other cylinder port to discharge;the crane also having a hoist line extending in part longitudinallyalong the boom and paying out to lower a load under control of a winchmotor and a three-position reversing ''''line'''' valve having up anddown conduits when the ''''line'''' valve passes pressured fluid to the''''down'''' conduit leading to the winch motor and makes a connectionfor the other winch motor conduit to discharge, said other conduithaving a pilotactuated safety valve preventing flow through said otherconduit from the winch motor to discharge except when pressured fluid issupplied to the ''''down'''' conduit, characterized by: a proportionalflow regulator connected to receive fluid from the ''''crowd'''' valvewhen in the ''''crowd'''' setting and to proportion the flow thereofbetween the ''''crowd'''' motor for extending the boom and the''''line'''' motor means for paying out the line; said three-positionreversing ''''line'''' valve when in its middle position blocking flowfrom the ''''down'''' conduit to discharge while providing a passage forflow from the other winch motor conduit to discharge.
 2. A hydraulicsystem for a crane having a boom which is telescopic under control of acrowd cylinder having extend and retract conduits and a reversing crowdvalve to be extended when the valve passes pressured fluid from a crowdpump to its ''''extend'''' conduit leading to one cylinder port andmakes a connection for the other cylinder port to discharge; the cranealso having a hoist line extending in part longitudinally along the boomand paying out to lower a load under control of a winch motor and athree-position reversing ''''line'''' valve having up and down conduitswhen the ''''line'''' valve passes pressured fluid from a line pump,having its output separate from the output of the crowd pump, to the''''down'''' conduit leading to the winch motor and makes a connectionfor the other winch motor conduit to discharge, said other conduithaving a pilot-actuated safety valve preventing flow through said otherconduit from the winch motor to discharge except when pressured fluid issupplied to the ''''down'''' conduit, characterized by: an adjustableproportional flow regulator connected to receive fluid from the crowdvalve when in the crowd setting and to proportion the flow thereofbetween the crowd motor for extending the boom and the ''''line''''motor means for paying out the line; whereby the line is payed out whenthe boom is extended, but at a relative rate which is adjustable; saidthree-position reversing ''''line'''' valve when in its middle positionblocking flow from the ''''down'''' conduit to discharge while providinga passage for flow from the other winch motor conduit to discharge.
 3. Ahydraulic system for a crane having a boom which is telescopic undercontrol of a crowd cylinder having extend and retract conduits and areversing crowd valve to be extended when the valve passes pressuredfluid from a crowd pump to its ''''extend'''' conduit leading to onecylinder port and makes a connection for the other cylindeR port todischarge; the crane also having a hoist line extending in partlongitudinally along the boom and paying out to lower a load undercontrol of a winch motor and a three-position reversing ''''line''''valve having up and down conduits when the ''''line'''' valve passespressured fluid from a line pump, having its output separate from theoutput of the crowd pump, to the ''''down'''' conduit leading to thewinch motor and makes a connection for the other winch motor conduit todischarge, said other conduit having a pilot-actuated safety valvepreventing flow through said other conduit from the winch motor todischarge except when pressured fluid is supplied to the ''''down''''conduit, characterized by: an adjustable proportional flow regulatorconnected to receive fluid from the crowd valve when in the crowdsetting and to proportion the flow thereof between the crowd motor forextending the boom and the ''''line'''' motor means for paying out theline; whereby the line is payed out when the boom is extended, but at arelative rate which is adjustable; said three-position reversing''''line'''' valve when in its middle position blocking flow from the''''down'''' conduit to discharge: but said valves providing a passagefor flow from the other winch motor conduit to discharge when the crowdvalve is set for extending the boom.